Net Loss Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net Loss Per Share [Abstract]
Net loss	$ (9,511)	$ (3,650)	$ (19,551)	$ (11,410)
Weighted-average common shares outstanding (in shares)	35,812	33,160	35,506	30,917
Net loss per share - basic and diluted (in dollars per share)	$ (0.27)	$ (0.11)	$ (0.55)	$ (0.37)
Stock options and restricted stock units (in shares)	5,206	5,605	5,148	5,966